map_to_string.rb

coords = [
  [-3, 0], [2, -3], [0, 0],
  [2, -4], [-1, -4], [-3, -2],
  [2, -1], [1, -4], [-2, -1],
  [-1, -3], [2, 0], [-2, -3],
  [2, -2], [-2, -2], [-2, 0],
  [-3, -3], [1, 0], [-3, -1],
  [0, -4]]

pre_normalized_coords = [
  [0, 4], [5, 1], [3, 4],
  [5, 0], [2, 0], [0, 2],
  [5, 3], [4, 0], [1, 3],
  [2, 1], [5, 4], [1, 1],
  [5, 2], [1, 2], [1, 4],
  [0, 1], [4, 4], [0, 3],
  [3, 0]]

def show_normalized_grid(normalized, center_x = 0, center_y = 0)
  # map to 2D array of strings
  grid = normalized.each_with_object([]) do |pair, result|
    (result[pair[0]] ||= [])[pair[1]] = ' '
  end

  # set center character
  grid[center_x][center_y] = '▢'

  # convert empty elements to spaces
  grid = grid.map{ |a| a.map{ |b| b.nil? ? '▉' : b } }

  # convert to string
  puts grid.map(&:join).join("\n")
end


# normalize the negatives
adjust_x_by = coords.min{ |a, b| a[0] <=> b[0] }[0] * -1
adjust_y_by = coords.min{ |a, b| a[1] <=> b[1] }[1] * -1

normalized = coords.map{ |pair| [pair[0] + adjust_x_by, pair[1] + adjust_y_by] }

puts '------'
show_normalized_grid(
  normalized,
  adjust_x_by, # because of 0,0 moving
  adjust_y_by) # because of 0,0 moving

puts '------'
show_normalized_grid(
  pre_normalized_coords,
  adjust_x_by, # because 0,0 isn't actually at 0,0
  adjust_y_by) # because 0,0 isn't actually at 0,0

output:

▉ = wall
▢ = origin
░ = walkable